Effect of Silica-coating over Rutile Titania Particles on the Suppression of their Photocatalytic Activity

Abstract

In order to reduce the photocatalytic activity of rutile titania particles (TOP (R)), two methods of silica-coating onto them were attempted. The amount of Ag photodeposited onto the particles per unit area, which was defined as the value of z, was calculated as an indication of their photocatalytic activities.
It was found that, when compared in the similar amount of silica-coatings, the z value of TOP (R) with silica-coatings prepared by a liquid phase deposition (LPD) method was approximately 0.1 times that by the general coating method. Transmission electron micrographs and the binding energy of Si_2p electron of the coatings determined by X-ray photoelectron spectroscopy (XPS) suggest that the superior effect of the former on the suppression of the photocatalytic activity is ascribable to the characteristics of the coatings by the LPD method, which are uniformity and a dense structure.